The present study showed that the FDG and AV45 (early-phase SUVR and SRTM2-based R1) indices were well correlated with the gold standard H₂O SUVR and may therefore serve as proxies of CBF. The within-subject correlations between R1 and eAV45 were likewise very high, indicating that the first 2 min of a dynamic AV45 scan—representing first-pass extraction of the tracer—can be representative for perfusion. Both the early phases and R1 of AV45 are of…